Explanation:
What's happening in the middle of this massive galaxy?
There, two bright sources at the centre of
this
composite x-ray (blue)/radio (pink) image are thought to be co-orbiting supermassive black holes powering the giant radio source
3C 75.
Surrounded by multimillion degree x-ray emitting gas, and
blasting out jets of relativistic particles the
supermassive black holes
are separated by 25,000 light-years.
At the cores of
two merging galaxies in the
Abell 400
galaxy cluster they are some 300 million light-years away.
Astronomers conclude
that these two supermassive
black
holes are bound together by gravity in a binary system
in part because
the jets' consistent swept back appearance is most likely due to their
common motion as they speed through the
hot cluster gas
at 1200 kilometres per second.
Such spectacular cosmic mergers are thought to be common in crowded
galaxy cluster environments
in the distant universe.
In their final stages the mergers are expected to be intense
sources of gravitational waves.